Nucleic Acid Synthesis Inhibitors Part 1

What are nucleic acid synthesis inhibitors?

Antimicrobial drugs that inhibit the synthesis or function of bacterial nucleic acids (DNA or RNA).

What are the four major classes of nucleic acid synthesis inhibitors?

Fluoroquinolones, rifamycins, nitrofurans, and nitroimidazoles.

Which class of nucleic acid synthesis inhibitors is most commonly used in veterinary medicine?

Fluoroquinolones.

What were the original quinolone drugs?

Nalidixic acid, oxolinic acid, and pipemidic acid.

What was the major limitation of the original quinolones?

Limited Gram-negative activity, bacterial resistance, and toxicity.

How were fluoroquinolones developed?

By modifying the 4-quinolone ring structure.

What is the general spectrum of fluoroquinolones?

Broad-spectrum.

What are fluoroquinolones generally classified as?

Bactericidal antibiotics.

What are rifamycins?

A group of structurally similar macrocyclic antibiotics produced from Streptomyces mediterranei.

Name the major rifamycins.

Rifamycin, rifampin (rifampicin), and rifamide.

Are rifamycins bactericidal or bacteriostatic?

Bactericidal.

What are nitrofurans?

Synthetic antimicrobial compounds derived from 5-nitrofuran.

Which nitrofuran group is essential for antimicrobial activity?

The 5-nitro group.

Name the commonly used nitrofurans in veterinary medicine.

Nitrofurantoin and nitrofurazone.

Which nitrofuran has been banned in food-producing animals?

Furazolidone.

Are nitrofurans bactericidal or bacteriostatic?

Bacteriostatic.

What is the general spectrum of nitrofurans?

Broad-spectrum.

What are nitroimidazoles?

Heterocyclic compounds with antibacterial and antiprotozoal activity.

Which drug is the prototype nitroimidazole?

Metronidazole.

Name the major nitroimidazoles.

Metronidazole, ronidazole, ipronidazole, and dimetridazole.

Are nitroimidazoles bactericidal or bacteriostatic?

Bactericidal.

Against which type of bacteria are nitroimidazoles primarily active?

Anaerobic bacteria.

Besides bacteria, what other organisms are nitroimidazoles active against?

Protozoa.

Which nucleic acid synthesis inhibitor class is especially effective against intracellular pathogens?

Fluoroquinolones.

Which nucleic acid synthesis inhibitor class is commonly combined with macrolides to treat Rhodococcus equi infection in foals?

Rifampin.

Which nitrofuran is mainly used for lower urinary tract infections?

Nitrofurantoin.

Which nitrofuran is primarily used as a topical antimicrobial?

Nitrofurazone.

Which nitroimidazole is commonly used for anaerobic bacterial and protozoal infections?

Metronidazole.

Why is metronidazole effective only against anaerobic bacteria?

Its activation requires anaerobic conditions.

Which two drug classes in this module are banned or restricted in food-producing animals?

Furazolidone and metronidazole.

What is the primary target of fluoroquinolones?

Bacterial DNA.

What is the primary target of rifamycins?

Bacterial RNA synthesis.

What is the primary target of nitrofurans?

Bacterial DNA and multiple microbial enzyme systems.

What is the primary target of nitroimidazoles?

Bacterial DNA after activation under anaerobic conditions.